Manufacture from sheet metal of pointed fastening devices



July 7, 1931. F. HUMPHRIS 1,813,805

I MANUFACT-URE FROM SHEET METAL OF' POINTED FASTENING DEVICES Filedinec. 2o, 1328y l l "l 11 ..1

` ATTORNEY Patented July 7, 1931 FRANK HUMPHRIS, or rARKsToNE, ENGLAND MANUEACTURE Enom SHEET METAL or roINrED EAs'rENINe DEvroEs Application inea iiecember 2o, 1928,? seriai No. 327,412, and in Great Britain December 21,1927.

This invention consists of improvements relating to the manufacture from sheet metal of pointed fastening devices having `hollowshanks. According to this invention a sheet 5 of metal, hereinafter referred to as the sheet,

is provided with what is described or hereinafter referred to as V-like perfor-ations or V-like slits, and the-said pointed fastening devices having hollow shanks and hereiny after referred to as fastening devices, are not severed,r bent or formed until after those parts'of such sheet from which they are to be' severed, have been perforated or slit by coaeting punches and dies mounted in rows in a press or like machine, which serve to cut the V- like perforations or V-like slits', 'or both, so as to forni a minimum of two of the converging edges of each pointed part 'of any fastening device subsequently made from such sheet. Itis to be understood that the said perforations or kslits are not limited in their shape so' as' torbe of exact V-like form and any perforations or slits which produce, as the result of their being formed in the said sheet, the converging edges of each pointed part of any' fastening device made from the said 'sheet vare intended tox be included in this invention;

Hitherto pointed and hollow shanked fas- V.30 tening devices have been blanked from a sheet of metal by punches a'nd dies which are so formed that they cut theV V-pointed end part, the shank and body part and-also `bend and form the hollow shape thereofinone operation; 4but great diihculty is experienced in hardening, tempering and sharpening the V-like ends of such combination gro'oved punches, their useful service period is short and they are very costly to maintain, as the cutting edges of their V-like ends have to be irregular and .tortuousto' venable them to also fold or bend the V-like ends of such fastening devices and irregular and t'o'ituous V-like ends on such punches make very inferior cutting edges, as they tear the material during blanking; the-'apices on the sharp pointed extremities of the Vv-,like ends of such combined grooved-punches, 'when in use, are subjected to high e'ofmpressive e0 stresses and sidestresses s'et'up during the bending or forming of the said hollow or channel-shanked shape of the pointed fastening devices and fracture results after a short period of use, and immediately the edges of the V-like form or the apices thereof become blunt, or the slightest fracture thereof occurs, the useful life of such coinbined grooved punches has been reached, as they can only be ground or sharpened on the converging edges of their V-like ends which reduces their size and also increases the clearance or distance between the said V-like converging edges and the V-like faces of the dies with which they coact and as a result the sheet metal is drawn into such clear'- ances and is torn instead of cut; by the use of the present invention su'ch diiiiculties are obviated and overcome.

An object of this invention is to provide a whole sheet or a part of a sheet of metal, through the medium of one or more rows of suitably formed V-like punches and their coacting dies, mounted in a press or like machine, and previous to actual pointedl fastening devices being cut therefrom, with one or more rows, as the case may be, of V-like perforations or V-like slits which are produced in such a manner that these are formed and located in all necessary parts of such sheet of metal at one and the same time or in a progressively arranged step by step manner. Another object of this invention is to form V-like perforations or V-like slits in a sheet of metal by means of cheaply produced and easily hardened and tempered V-like punches and their coacting dies, so that the other punches and dies subsequently used for blanking and formingpointed fastening devices from such sheet of metal do not have to be provided with V-like pointed end parts. The invention will now be described with reference to the accompanying drawings, in which y Figure 1 is a face view of a piece ef a sheet of metal broken from one corner thereof, to illustrate how such sheet is, previous Y sheet of metal broken from one corner thereof, to illustrate how such sheet is, previous to the pointed fastening devices shown in dotted lines being subsequently cut therefrom, provided with V-like slits.

Figure 3 is a face view of a piece of a sheet of metal broken from one corner thereof, to illustrate how such sheet is, previous to the pointed fastening devices shown in dotted lines being subsequently cut therefrom, provided with double V-like perforations.

Figure A is a perspective view of a gro'oved punch as ordinarily used to form single pointed fastening devices of the kind indicated in dotted lines in Figure 2, it is enlarged relatively to the other illustrations.

Figure 5 is a perspective view of a grooved punch as ordinarily used to form double pointed fastening devices of the kind indicated in dotted lines in Figure l, it is enlarged relatively to the other illustrations.

Figure 6 is a perspective view of a J -like punch of the kind used to form the V-like perforations in a sheet of metal as shown in Figure 1.

Figure 7 is a perspective View of a J -like punch of the kind used to form the V-like slits in a sheet of metal as shown in Figure 2 Like letters of reference refer to like parts throughout the drawings.

A sheet of metal A is, according to this invention, provided with so-called il-like perforations a or V-like slits al by means of suitably formed punches and dies before the said sheet A is passed between so-called article-producing punches and dies for the purpose of having pointed fastening devices made therefrom, which condition make it unnecessary for the said article producing punches and dies to be provided, as must ordinarily be done, and means for also blanking the so-called il-like point parts of the said pointed fastening devices, as by carrying this invention into effect this is done previously and at the time when the so-called V -like perforations a or V-'like slits al are cut in the said sheet, thus obviating the necessity for the blanking or cutting of such so-called V -like pointed parts at the same time as the body or shank and head parts are blanked and formed by the said article producing punches and dies, and these, when the il-like perforations a or V-like slits al are employed, as described in this invention, only have to serve to bend or to give the channelled or crinkled crosssectional form to the so-called `\.!-likel point parts of the said fastening devices at the same time as the body or shank and head parts thereof are also cut out and bent. channelled, crinkled or folded thereby. i

Sheets of metal A provided with so-called V-like perforations a2 which are double or side by side as disclosed in this invention and illustrated in Figure 3 of the drawings are also advantageously employed in producing the known forms 0f driven fastening devices having a double-V or W-like form at the point part of the blanks from which they are made when the known follow-on process is employed and these perfo'rations a2 in the said sheet A are so -located that they cut away asrdo also the perforations a what would otherwise be obstructing parts a3 of the said sheet A which if left in such sheet A prevent folding punches of full length being employed; `but by the use of sheets of metal A having V-like perforations a ofr a2 or V-like slits al formed in such sheet of metal A previous to the folding or bending of the said pointed fastening devices permits-full length folding punches to befemployed for this purpose which could not' otherwise occur and the said single or double-V-like or W-like formed points of such fastening devices to be both folded centrally and accurately and at the correct pitch distance apart.

Punches as ordinarily employed for the purpose of making the fastening devices and as illustrated in Figures 4 and 5 of the drawings have a short life and always rstly collapse or break at the parts thereof which form the points of the Said pointed fastening devices and in practice it has been found that to properly harden and temper these point forming parts and atvthe same time also properly harden and temper the thicker or more massive parts integral therewith which serve for blanking out and folding-the shanks and head parts of the said pointed fastening devices is most difficult,

slow and costly, as those parts thereof which form the extremities of the points of the pointed fastening devices, are during the heating process for hardening usually burned and when quenched and tempered are too brittle unless the shank and head forming parts are made-far too soft to maintain a commercially useful life.

I claim: V

l. Sheet material prepared for use in the manufacture of pointed fastening devices by means of a press and having a number of slits formed therein in rows extending both longitudinally and transversely of the sheet, the said slits being respectively limited in shape and position to the point parts only of fastening devicesto be formed from the sheet.

2. Sheet material prepared for use in the manufacture of pointed fastening devices by cutting blanks therefrom, said sheet having a number of slits formed therein corresponding in number to the blanks to be cut and limited in shape to theV point portion only of the said blank, and each slit corresponding to a blank being spaced apart from parts 

